Agricultural chisel plows and field cultivators are equipped with a plurality of earthworking tools that are moved through the soil to break and roll the soil in preparation of a seedbed. The earthworking tools are mounted on frames and tool bars with clamps having spring trip mechanisms. The spring of a trip mechanism is deflected when the tool hits an obstacle so that the tool moves to a trip position and rides over the obstacle. The biasing force of a deflected spring increases in relation to the amount of deflection. This increases the forces on the tool as it moves from the earthworking position to the trip position. These forces can cause bending and breakage of the tool. Example of spring trip mechanisms for earthworking tools are disclosed in U.S. Pat. Nos. 2,712,780; 4,005,757 and 4,011,916.